As the demand for food throughout the world increases, a great deal of effort has been expended finding ways to more efficiently produce food, both animal and vegetable, to satisfy the demand. Sea life, including crustaceans and fish, has long been a source of high quality protein for human consumption. However, harvests of wild populations have, in recent years, been severely restricted because of environmental contamination problems and over-fishing. Fish catches have become much smaller and it has been difficult to keep fishing grounds productive. Attempts have been made to grow monocultures of aquatic animals (e.g., shrimp farming) under varying levels of controlled conditions. Often such farms provide a large proportion of a particular kind of seafood consumed. For example, approximately half of the penaeid shrimp consumed in the United States in 1993–94 were from farms. Aquaculture systems of the prior art (mariculture systems for marine organisms) are either open (i.e., water is constantly replenished from an outside source) or closed (i.e., the same water is recirculated through the system).
Successful mariculture has been undertaken mainly in coastal areas using estuarine or coastal waters. Efficient production of crustaceans, fish, and shellfish have been undertaken by surrounding part of a marine area such as a gulf, a bay or an estuary having favorable conditions with nets, or by building ponds on land which take advantage of the tidal flow from the sea or pumping water from the ocean. Large shrimp farms have thus been built in the coastal zones of Latin American and Southeast Asian countries. In the past these shrimp culture systems relied partially on the eco-systems and marine food chains that developed in the rearing ponds to supply the feed for the shrimp. Today, natural foods produced in ponds are supplemented by shrimp feed, and the natural food chains are stimulated by the addition of fertilizer.
A disadvantage to known open mariculture systems, i.e., those systems which rely on natural sea or brine water sources and which are constantly exposed to the environment, is that water quality in estuaries and near shore areas may vary greatly depending upon the nature of the effluents from the land. Herbicides, pesticides, and other agricultural effluents may thus find their way into mariculture systems in affected areas. Similarly, industrial or urban effluents may adversely affect the water quality for such mariculture systems in coastal areas. An example of the deleterious effects of chemical effluents on the culture of marine life is Taura syndrome, which has afflicted the shrimp farming industry in certain tropical locations. Afflicted juvenile shrimp stop feeding, become lethargic, and ultimately die. It appears that the syndrome is caused by high levels of agricultural chemicals in the shrimp culture water, especially fungicides, which are heavily used by agricultural concerns in the affected region. Chemical pollution by agricultural chemicals has also adversely affected shrimp harvests in Latin and South America and Southeast Asia. In addition to mortality due to chemical contaminants, shrimp are susceptible to infection by a variety of viral and bacterial pathogens, such as parvoviruses, baculoviruses, Vibrio, and necrotizing hepatopancreatitis bacterium. Infection with these pathogens result in significantly reduced yields of shrimp. Thus, elimination of the etiological agents of Taura syndrome and infectious diseases of shrimp would be of great utility to the shrimp farming industry in particular, and to the mariculture industry in general.
In light of these problems, there have been attempts to practice mariculture in closed loop systems, by providing a culture environment in a tank installed on land. According to these methods, the problem of environmental contamination can be avoided by isolation of the culture system from natural water sources and by recirculating culture water. The recirculated water is purified by biofiltration, ozonation, foam fractionation, and denitrification to remove pollutants and minimize water exchanges. Several such methods and arrangements for breeding aquatic life in closed systems have been described by the prior art (see U.S. Pat. Nos. 5,076,209 by Kobayashi, et al.; U.S. Pat. No. 4,052,960 by Birkbeck, et al.; U.S. Pat. No. 4,394,846 by Roels; and U.S. Pat. No. 3,973,519 by McCarty, et al.).
Open systems are to date, however, the only systems of sufficient magnitude to support commercially viable operations. The volumes of water necessary for economical mariculture operations can only be obtained from natural water sources, i.e., salt lakes, estuaries, and seas.
U.S. Pat. No. 4,209,943 to Moeller et al. discloses a system for and method of culturing marine algae in a water charged atmosphere, wherein the algae being cultured is not completely immersed in water. Rather, the algae is cultured in a thin film of water containing the required nutrients, while the upper portion of the species is exposed to a high humidity atmosphere containing carbon dioxide.
U.S. Pat. Nos. 4,199,895 and No. 4,115,949 to Avron et al. disclose a process for the simultaneous production of glycerol, carotenes (β-carotene, its isomers and carotene-like substances) and protein rich material. The process comprises the steps of: cultivating the alga Dunaliella bardawil under high-intensity illumination in a growth medium containing a high concentration of sodium chloride (at least 1,5 M in the final stage of the cultivation); providing an adequate supply of carbon, in the form of CO2, in a depth of not exceeding 20 cm of the aqueous medium, in a diurnal cycle of illumination, until algae of high content of the above three components are obtained; and harvesting the algae and recovering from same the three constituents.
U.S. Pat. Nos. 5,947,057 and No. 5,732,654 to Perez et al. disclose a mariculture system and method of culturing marine life with a polluted source water. The system includes a water replenishment reservoir, activated carbon and ozone purification devices, a device for removing toxic byproducts of ozonation of salty or brackish (bromine-containing) water, and ponds for the culture of marine animals. The method includes obtaining water containing compounds and organisms detrimental to marine animal life, treating the water so it is suitable for the culture of marine animals, and raising and harvesting marine animals in the treated water.
U.S. Pat. No. 4,394,846 to Roels discloses a method of utilizing ocean water for the culture of marine species. The method includes maintaining a flow of ocean water through a finfish culture unit and supplying finfish feed to the unit for the culture of finfish therein. The method further includes maintaining a flow of finfish culture unit effluent through a shrimp culture unit and supplying plankton nutrients to that unit for the culture of plankton to constitute part of the feed for the culture of shrimp, and maintaining a flow of shrimp culture unit effluent through a filter feeder unit for the culture of filter feeders therein. The effluent from the filter feeder unit is fed to a seaweed culture unit for the culture of seaweed and clarification of the effluent, after which the clarified effluent is discharged.
U.S. Pat. No. 4,869,017 to Bird et al. discloses a method for the production of macroalgae, e.g., Gracilaria, in a marine culture system. Improving the manner in which the aqueous culture medium is created enhances the production. First, the alkalinity of a quantity of freshwater is adjusted by the addition of an alkaline reagent thereto. Then seawater is diluted with alkalinity-adjusted freshwater to create a saline solution having a salinity of between about 15 to 25 parts per thousand and an alkalinity of between about 3 to 10 meq/l. Then, carbon dioxide is dissolved in the resulting solution to bring its pH to between about 7.5 and 8.5. The carbon dioxide enriched solution is then used as the culture medium. Other macroalgae disclosed include Agardhiella, Porphyra, Gelidium, Pterodadia, Laminaria, Hypnea and Chondrus. 
U.S. Pat. No. 6,258,588 to Demetropoulos et al. discloses Palmaria cultivars having a growth rate greater than wild type and known strains, particularly when cultured at temperatures greater than about 16° C., and specific embodiments of such cultivars, many of which have a rosette morphology. Methods for isolating such cultivars and using the cultivars as a food source also are described. Isolated Palmaria cultivars can be used as a food source for feeding organisms, such as humans.
U.S. Pat. No. 4,417,415 to Cysewski et al. discloses a method of culturing Porphyridium cruentum in an enriched seawater using a high initial cell concentration. The seawater is enriched with a soluble nitrate and a soluble phosphate. A hydrophilic colloidal polysaccharide produced by P. cruentum is isolated by extraction by making the culture strongly alkaline, and heat-treating it. The culture is then cooled, and acidified and the polysaccharide precipitated by addition of a water-miscible organic solvent such as ethanol. Cysewski et al state that it is not practical to artificially culture macroalgae on the scale necessary for large-scale polysaccharide production, due to their large size and the resultant space required. Accordingly, the macroalgae must be harvested from their natural sites in shallow water near to seacoasts. However, many of the coasts on which the macroalgae occur are rocky and are subject to severe storms at certain times of the year. The growth of the macroalgae in various parts of the United States is hindered by over-harvesting, coastal water pollution, sea urchin infestation and other factors. Moreover, the labor involved in harvesting natural macroalgae is difficult arduous and expensive. Furthermore, the macrolagae may be contaminated by large amounts of foreign matter, such as sand, and require considerable pretreatment to remove such foreign matter before the polysaccharide is extracted from the macroalgae. They state it is difficult to produce a consistent product from macroalgae, and it is necessary to monitor very closely the properties of the polysaccharide, and often to blend polysaccharide from different batches of seaweed, in order to ensure that the thickening properties of the polysaccharide remain constant, since such properties vary not only with the type of seaweed and the site on which it grows, but also with the time of the year.
In view of the difficulties associated with the production of polysaccharides from macroalgae, attempts have been made to extract such polysaccharides from microalgae, several of which are known to exude polysaccharides into the medium surrounding them at various stages during their life cycle (Percival and Foyle, Carbohydrate Research (1979) 72, 165–176). U.S. Pat. No. 4,087,936 to Savins et al. and M. L. Anderson, describes a process for the extraction of a polysaccharide from P. cruentum. This process is carried out in fermentation vessels using either artificial light or sunlight and the process reportedly can be better controlled than can a process using marine macroalgae. Such processes using microalgae under closely controlled conditions can be expected to yield a much more uniform product than is usually obtained from marine macroalgae.
The cultivation of microalgae to recover biopolymers as well as other products in the algal biomass is well known in the art. Such algae biopolymers are useful in various applications such as thickening agents for mobility control in waterflood oil recovery, as food additives, as flocculants useful in waste water treatment, soil conditioning, and as drilling mud extenders. Cultivation of the algae requires a nutrient medium containing nitrogen and other mineral nutrients and micronutrients, a source of assimilable carbon, illumination with light energy, and favorable conditions of temperature, pH, and salinity. Normally carbon dioxide is employed and this is required in the case of the obligate photoautotrophs that are capable of growth only by photosynthetically incorporating carbon dioxide. However, in the case of algae capable of photoheterotrophic growth, assimilable carbon may be provided by a pre-formed organic carbon source such as glucose, mannose, fructose, either alone or in combination with carbon dioxide.
Zeaxanthin and lutein are xanthophylls that can be extracted from marine algae such as Dunaliella salina. Lutein and zeaxanthin find widespread application in the feed additive, neutraceutical, cosmetic, and pharmaceutical industries. They serve important functions for human vision. One major example is the macula, the tiny portion of the retina responsible for 20/20 vision, where lutein and zeaxanthin supplementation slow Age related Macular Degeneration (AMD). Research further indicates that because of its antioxidant properties lutein consumption may play a role in protecting the heart, skin, as well as the breasts and cervix in women. Until now, the only viable source of harvestable lutein was marigold flowers, while no commercially viable process for zeaxanthin production existed
Borowitzka et al. (Bull. Marine Science (1990), 47(1), 244–252; and Hydrobiologia (1984), 116/117, 115–134) disclose a method for the commercial production of β-carotene by Dunaliella salina in open-air ponds. A mixture of seawater and freshwater or brine and seawater or brine and freshwater are used as the water source for aquaculture. Additional nutrients are generally also added to the water. The culture conditions are optimized for the production of β-carotene by controlling water salinity, vertical and horizontal distribution of the algal mass, nutrient levels in the water, pond depth, and accumulation of rainwater runoff into the pond.
U.S. Pat. No. 4,581,233 to Herve et al. discloses the isolation of protoexoplasm from algae and the use of the protoexoplasm as a potential therapeutic material. U.S. Pat. No. 4,439,629 to Ruegg discloses the isolation of β-carotene and/or glycerin from Dunaliella sp. algae. U.S. Pat. Nos. 4,390,624, No. 4,383,039 and No. 4,383,038 disclose the production of L-proline from Chlorella sp. algae. U.S. Pat. No. 4,341,038 to Bloch et al. discloses the isolation of an oil low in sulfur content from Dunaliella sp. algae. U.S. Pat. No. 4,913,915 to Tanaka discloses a solid foodstuff made from Dunaliella sp. algae. The foodstuff is rich in β-carotene and is nutritious. U.S. Pat. No. 4,851,339 to Hills discloses a process for the isolation of carotenoid, tetrapyrrole and porphyrin by extraction of Spirulina sp. or Dunaliella sp. algae.
U.S. Pat. No. 2,949,700 to Kathrein discloses a method of obtaining carotenoids and xanthophyll by cultivating Chlorella vulgaris and C. pyrenoidosa algae in artificial seawater and isolating the carotenoids from the algae.
U.S. Pat. No. 4,780,534 to Lebbar et al. discloses a process for the preparation of agar-agar gel from an extract of red algae Gelidium sesquipedale. Agar-agar is a mixture of polysaccharides (agarose, agaropectin) of high molecular weight between 40,000 and 300,000 daltons. It is made generally by producing algae extracts by autoclaving the algae and treating the extracts to remove calcium iron and magnesium ions. The agar is then precipitated at low temperature. The extracts must contain about 2% of agar-agar in order to extract the agar-agar.
U.S. Pat. No. 4,744,996 to Rakow et al. discloses a foodstuff comprising a microalgae embedded in a matrix.
U.S. Pat. No. 4,690,828 to Kitahara et al. discloses a coagulated food made from brown algae. The coagulated food product can be prepared by entirely liquefying with sodium citrate each of the two kinds of brown algae (seaweed), i.e. makombu (Laminaria japonica) and wakame, or makombu and hondawara (Sargassum fulvellum), into a solution or a viscous liquid, mixing the obtained solutions or viscous liquids, and coagulating the mixture with calcium chloride etc. (see Japanese Patent Laid Open No. 99179/1982). Other suitable brown algae include arame (Eisenia bicyclis), kajime (Ecklonia cava), hijiki (Hizikia fusiforme), hondawara, or a combination of these brown algae and kombu or wakame.
Spirulina is a planktonic blue-green algae with an amazing ability to thrive in conditions much too harsh for other algae. It has a highly unusual nutritional profile. Spirulina has a 62% amino acid content, is the world's richest natural source of Vitamin B-12 and contains a whole spectrum of natural mixed carotene and xanthophyll phytopigments. Spirulina has a soft cell wall made of complex sugars and protein, and is different from most other algae in that it is easily digested. Millions of people worldwide eat Spirulina cultivated in scientifically designed algae farms. Current world production of Spirulina for human consumption is more than one thousand metric tons annually. The United States leads world production followed by Thailand, India and China. More countries are planning production as they realize it is a valuable strategic resource.
Saline aquifers are known to exist in many parts throughout the United States. However, those aquifers have compositions that are not suitable for aquaculture.
Thus, none of the known art discloses a system for or method of culturing marine species in an open-air system containing water obtained from a saline aquifer such that seawater or brine are not required. Such a system could be operated inland away from the sea. Prior to the present discovery and invention, no suitable inland water source had been identified. A need remains for improved systems for and methods of inland aquaculture of marine species.